Field of Invention
The disclosed embodiments relate generally to portable computing devices and mobile electronic devices with display screens, and more particularly, to portable computing devices and mobile electronic devices that interpret user motions of the device to scroll and zoom a display screen.
Description of Prior Art
As portable computing devices become smaller, the size of their display screens have become smaller. A small display screen, one that is much smaller than a desktop or laptop computer's display screen, presents a significant challenge to provide a user interface that allows users to easily interact with a computing device without interfering with the displayed content of the device. The user interface not only allows users to view content, but a user interface is required to allow the user to view the extents of all the content that the device is capable of providing. Some portable computing devices have resorted to adding finger gestures to replace common user interface objects, such as scroll bars and zoom sliders. Finger gestures represent an improvement as finger gestures usually do not place objects on the display screen and they are simple to use. But finger gestures also suffer from the following undesirable effects: Two hands are generally required to scroll. One hand is used to hold the device while fingers on the other hand are used to scroll and/or zoom the screen. Also, the user's fingers are in the way of viewing the display screen during the time the scroll and/or zoom commands are executed. This results in a two step process. First the user performs the hand gestures to scroll or zoom the display screen. Then the user may see the changes to the display screen without the user's fingers in the way.
The conventional user interface for scrolling is scroll bars. These scroll bars require screen real estate and limit the amount of content that can be viewed on the display screen. Using a scroll bar on a small portable communications device requires precision input as the scroll bars are very small and errors are common. Scroll bars, as with finger gestures, require the user's fingers, or a stylus, to be on the screen which may interfere with viewing of the screen display. Using both scroll bars, with the user's fingers, and finger gestures require the touching of the screen which can smear the screen with contaminants from the hands.
To avoid problems associated with finger gestures and scroll bars, portable computing devices may use screen displays with an accelerometer that detects user motions on the screen and translate detected motions into scrolling or zooming commands to be performed by the visible program.
Image shifting of the display screen has been previously implemented in portable devices. A common device to include this capability is digital cameras. Digital cameras shift images on their display screens to stabilize pictures. However, shifting an image on screen does not move significant off screen display content on to the display screen, as does scrolling. Scrolling, through user motion, enables the user of a portable device to view previously unseen screen content with user intended device motion.
Accordingly, there is a need for portable computing devices with a more transparent and intuitive user interface for viewing content beyond the physical limits of the display screen. Such an interface will increase the effectiveness, efficiency and user satisfaction with portable computing devices.